package/bitcoin: set BITCOIN_GENBUILD_NO_GIT

Set BITCOIN_GENBUILD_NO_GIT to not include (Buildroot) git version info in
build, which is available since version 0.15.0 and
https://github.com/bitcoin/bitcoin/commit/e98e3dde6a976a2c8f266ee963d6931fd4b37262

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 82d6abda1a84a2fc126af0bbda532bd545073c0e)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/bitcoin/bitcoin.mk

@@ -10,6 +10,7 @@ BITCOIN_AUTORECONF = YES
 BITCOIN_LICENSE = MIT
 BITCOIN_LICENSE_FILES = COPYING
 BITCOIN_DEPENDENCIES = host-pkgconf boost libevent
+BITCOIN_MAKE_ENV = BITCOIN_GENBUILD_NO_GIT=1
 BITCOIN_CONF_OPTS = \
 	--disable-bench \
 	--disable-wallet \